1. Field of the Invention
The present invention relates to a method for producing a fluid trap for a film assemblage containing a peel-apart type instant film unit.
2. Description of the Related Art
Self-developing type instant film units are generally classified into mono-sheet type units and peel-apart type units, the latter of which have been used for a long time. The peel-apart type instant film unit includes a photosensitive sheet and an image receiving sheet, which are connected together via a connecting sheet and are separately accommodated at opposite sides of a body of the unit. The peel-apart type instant film unit is hereinafter simply referred to as a xe2x80x9cfilm unitxe2x80x9d. After exposure, as a user pulls a drawing sheet from a nip between a pair of spreading rollers, the photosensitive sheet and the image receiving sheet are overlapped with each other via movement of the connecting sheet connected with the drawing sheet. As the overlapped sheets are further pulled, a pod containing a developing solution is ruptured by the pair of spreading rollers and the developing solution is spread between the photosensitive sheet and the image receiving sheet.
An image frame sheet is separably attached to the image receiving sheet, and spacers are adhered to the image frame sheet at opposite ends thereof in a direction substantially perpendicular to a direction in which the image receiving sheet is pulled. The image frame sheet is hereinafter also referred to as a xe2x80x9cmaskxe2x80x9d. The spacers are hereinafter also referred as xe2x80x9crailsxe2x80x9d. A spreading width of the viscous developing solution contained in the pod is determined by a distance between the pair of spacers. A spreading thickness of the viscous developing solution is regulated by a total thickness of the mask and the rail. In order to evenly spread the viscous developing solution between the image receiving sheet and the photosensitive sheet, and in order to prevent defects due to insufficient spreading of the developing solution, the pod contains a slightly excessive amount of the developing solution. Then, a portion of the developing solution remaining after the developing solution has been spread within an area in the image frame is stopped by fluid traps, which are disposed at the spacers. Each of the fluid traps is formed to have a trapezoidal or semicylindrical sectional form. A height of the sectional form of the trap is several times greater than the total thickness of the mask and the rail. Therefore, a spreading thickness of the developing solution in the area near the fluid traps is several times greater than a spreading thickness of the developing solution in other areas, and a spreading length is reduced by several times. Therefore, the developing solution does not leak out of the film unit.
The fluid trap is produced by: using polyvinyl chloride to form a continuous body of polyvinyl chloride by profile extrusion, applying a hot melt coating to the formed continuous body, and cutting the continuous body. The fluid trap is slow to set during profile extrusion and significantly deforms when the continuous body is taken up on a reel. Thus formed, the continuous body of polyvinyl chloride is not easily machined and produces a large amount of cutting waste. Further, plastic extrusion requires water cooling for maintaining a trap shape of a base material after the hot melt coating is applied to the base material. Therefore, a large system is necessary. Because of the slow forming speed and the large system, overall costs of producing the trap become large.
Moreover, these days, people are paying attention to how businesses make efforts to reduce environmental problems. It is becoming a social responsibility for those who sell products to reduce negative impacts of their products on the environment as much as possible. As a result, there is demand for using a more environment-friendly material, rather than a formed material made of a resin such as polyvinyl chloride.
Therefore, a task of the present invention is to solve the above-described conventional problems and achieving the following object. An object of the invention is to provide a method for producing a fluid trap for an instant film assemblage, which method can produce an environment-friendly trap easily and at low costs.
The above-described object is accomplished by a method for producing a fluid trap for an instant film assemblage disclosed herein. First, an instant film assemblage in the method of the invention contains at least one peel-apart type instant photographing film unit. The film assemblage includes a body. The body includes a substantially rectangular parallelepiped box-like case body including an exposure opening formed on a top surface thereof and a film unit ejection port formed on a front wall continuous to the top surface. Further, a film platen is accommodated between the top surface and a bottom surface of the case body. A photosensitive sheet connected with a drawing sheet is accommodated on an upper surface of the film platen such that the photosensitive sheet is oriented to the exposure opening. An image receiving sheet connected with the drawing sheet via a connecting sheet is accommodated under a lower surface of the film platen. The photosensitive sheet, the image receiving sheet and the drawing sheet are disposed such that when a tip of the drawing sheet projecting from the ejection port is pulled by an operator, the photosensitive sheet and the image receiving sheet overlap each other and are pulled out from the ejection port. The drawing sheet includes a developing solution pod. At least one spacer for regulating a developed thickness of the developing solution is separably adhered to the drawing sheet at opposite end portions in a direction substantially perpendicular to a direction in which the image receiving sheet is drawn. At least one fluid trap is disposed at at least one development terminal end of the at least one spacer.
According to the invention, the trap is produced in the following manner. A plate-shaped paper material having a uniform width and a uniform thickness is moved through a clearance formed between a pair of rollers. The plate-shaped paper material is compressed at width-directional opposite end portions thereof such that a thickness of the paper material gradually decreases from a central portion thereof toward opposite ends thereof, and at the same time, the paper material is cut along a longitudinal direction thereof to a predetermined width. Thereafter, the paper material is cut along the width direction thereof at predetermined intervals with respect to the longitudinal direction thereof.
The plate-shaped paper material may have a basis weight ranging from 300 to 500 g/m2. Further, the plate-shaped paper material may have an apparent density ranging from 0.55 to 0.65 g/m3.